Polymers of carbon monoxide and olefins generally referred to as polyketones are well known in the art. Of particular interest among polyketone polymers, is the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon. This class of polymers is disclosed in numerous U.S. patents assigned to Shell Oil Company, exemplified by U.S. Pat. No. 4,880,865 which is herein incorporated by reference.
Although the properties of polyketone polymers are suitable for many applications, linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon do exhibit a deterioration of physical properties upon thermal oxidative degradation. This degradation is due to a chemical attack of atmospheric oxygen on the polymer chains and is characteristic of most, if not all organic polymers. Oxidation is typically autocatalytic and occurs as a function of heat and oxygen, hence the term thermal oxidative degradation. It is desirable to inhibit the deterioration of polymer properties by stabilizing the polymer toward the adverse effects of heat and oxygen. There are a large number of thermal oxidative stabilizers which are employed commercially to stabilize thermoplastic polymers against such degradation. However, many of the thermal stabilizers which are known to be effective with polyolefins, polyamides, polyacetals, polyacrylates, etc. are only marginally or not at all effective when employed with polyketone polymers. It would therefore be of advantage to provide polyketone polymers which demonstrate improved heat stability to extend their use in higher temperature applications.
It is known that upon synthesis polyketone polymers contain a variety of impurities. These impurities include residual solvents such as methanol, ketal defects , residual catalyst components, and metal ions. The presence of these impurities is believed to adversely affect the stability of the polymer, and it is believed that their removal or reduction will enhance the stability of the polymer. Consequently, the discovery of methods and techniques for the removal of these impurities are desirable, and will be beneficial to the art and the industry.